Think Trump’s wrong? Fact checkers can tell you how often. (Hint: A lot.)

No, Donald Trump, the unemployment rate isn’t 42 percent. And, no, it’s not true that President Obama wants to take in 250,000 Syrian refugees. Or that “thousands and thousands” of American Muslims celebrated when the World Trade towers toppled on 9/11. Despite numerous accounts to the contrary, Trump has insisted on all these things.

Holan, the editor of PolitiFact, the Pulitzer Prize-winning news site devoted to vetting political statements, has investigated plenty of dubious assertions in her time. But she’s never seen anyone quite like Trump.

“The difference with him is the degree to which he’s wrong,” she says. “All politicians like to stick to their talking points, and sometimes a few of those points are debunked. With Trump, it’s not one or two points. It’s lots and lots.”

Politicians of every kind, in every era, have bent and twisted facts to their liking. And, yes, (shocker!), they sometimes lie. But to Holan and the small community of professional fact- checkers, Trump represents something new: a front-running candidate who isn’t just wrong at times, but wrong many, many times, and defiantly so when called on it.

● The Washington Post’s Fact Checker column has awarded Trump four Pinocchios — its lowest rating for honesty — 63 percent of the time it has looked at one of his statements, also by far the worst percentage (others: Cruz, 21 percent; Rubio, 18; Sanders and Clinton 14). A recent four-Pinoc: Trump’s claim that a wall along the U.S.-Mexico border would cost $8 billion.

● In naming Trump the “King of Whoppers” in its annual review last year, FactCheck.org, an organization at the University of Pennsylvania, observed: “In the 12 years of FactCheck.org’s existence, we’ve never seen his match. He stands out not only for the sheer number of his factually false claims, but also for his brazen refusals to admit error when proven wrong.”

It’s not clear that Trump has ever backed down from any of his unsubstantiated claims since announcing his candidacy in June — a hallmark of his pugnacious style. When journalists failed to find TV footage or published accounts to back up Trump’s assertion of widespread celebrations in New Jersey cheered on 9/11, for example, Trump cited “hundreds” of calls and tweets from people claiming they’d seen the same thing. He demanded an apology from those who’d written otherwise.

He has also questioned the fact-checkers. After PolitiFact awarded Trump its “Lie of the Year” for his run of campaign misstatements, he responded by telling ABC News, “They are leaning in a certain direction, and no matter what you do with them — I mean they are a very dishonest group, in my opinion.”

Trump’s refusal to acknowledge error, or to simply adjust his rhetoric, sets him apart from his fellow office-seekers, too: Contrary to the general cynicism about political truthiness, many leading politicians do change their tune when called out on untrue statements, fact-checkers say. Sanders, for one, changed a talking point about the chances of a black male being sent to prison after The Post’s Fact Checker questioned his data.

“Professional politicians mostly want to get it right,” said Glenn Kessler, the Fact Checker columnist. “What’s unusual about Trump is he’s a leading candidate and he seems to have no interest in getting important things factually correct.”

And that fact isn’t especially frustrating to the fact-checkers. Their goal, they say, is to point out what’s wrong, not necessarily to change a politician’s ways.

“The mission of the fact-checker is to inform democracy, first and foremost,” said Bill Adair, PolitiFact’s creator and now a journalism professor at Duke University. “So it doesn’t bother me to say that a statement is false and a candidate continues to make that statement. The most important thing is that we’re telling voters what’s true and what’s not.”

Fact-checkers haven’t failed if politicians continue to twist the facts, Adair said, any more than investigative reporters have failed when politicians continue to be corrupt.

In fact, an academic study of political fact-checking operations this year found that the public generally views political fact-checking favorably, and that more exposure to it helps people become better informed. However, the study also found that the format tends to reach already well-informed and educated people and that those who are less informed have less favorable views. What’s more, the study found a partisan divide: Republicans find less to like in fact-checking than Democrats, an echo of conservative complaints that fact-checkers are slanted against Republicans.

As for Trump, it’s possible that his supporters are less interested in mere facts than in other qualities, such as his determination, passion and strength, said Carol Pogash, the author of “Quotations From Chairman Trump,” a recently published collection of his statements through the years. “His fans . . . are voting for the Disrupter-in-Chief,” said Pogash. “He’s the billionaire who promises to blow up the status quo. His supporters love that Trump is the bully in the china shop.”